The present invention relates generally to recloser relays, and more particularly, to a relay spare circuit for use with such recloser relays.
Recloser relays are typically provided to control the reclosure of a fault-responsive circuit breaker. Relay spare circuits are typically provided to alter or control the operation of the associated power system during a reclose cycle, or to control when in a reclose cycle certain fault-responsive relays are to operate an associated circuit breaker. For example, relay spare circuits may be used to provide such functions as blocking automatic load-ratio control, blocking the instantaneous trip circuit following a second reclosure, or as a spare contact in reclosure applications such as to provide a spare alarm contact.
The timing of a reclose cycle is generally regulated by a rotating cam shaft which operates in conjunction with associated, mechanically operated switches. Examples of such systems may be found in U.S. Pat. Nos. 3,381,177, issued to W. P. Allen, and 3,333,154 and 2,582,027, issued to L. E. Goff, Jr. In additon to regulating the reclose cycle, such systems may also be used to similarly regulate operation of the relay spare circuit.
However, because the high spot on a cam has a fixed width, the time delay associated with the relay spare circuit is limited to a function of the rotation of the cam, and accordingly, the overall reclose cycle. Moreover, such cam shaft operated mechanisms do not readily permit the selection of the portion of the reclose cycle at which the relay spare circuit is to be operated. It is therefore desirable to perform the same function electronically, to remove these dependencies and provide a more versitile relay spare circuit. Further, it is desirable to develop such as relay spare output without requiring the use of a plurality of separate switches and timers to do so.
Accordingly, it is a primary object of the present invention to develop a relay spare circuit which is capable of electronically developing a desired relay spare output.
It is a further object of the present invention to develop a relay spare circuit which is capable of electronically developing a desired relay spare output without requiring the use of a multiplicity of switches and timers.
It is a further object of the present invention to provide a relay spare circuit having the ability to select when in the reclose cycle the relay spare output is to occur.
It is a further object of the present invention to provide a relay spare circuit including a series of switches which may be utilized by an operator to select when in the reclose cycle the relay spare output is to occur.
It is a further object of the present invention to provide a relay spare circuit with a priority function which assists in the correction of inadvertent or erroneous setting of the operator selected switches.